INTRASPECIFIC INTERACTIONS OF MELOIDOGYNE-JAVA']JAVANICA AND RACES OF MELOIDOGYNE-INCOGNITA

The intraspecific interactions (competition among the individuals in the same species/race) of Meloidogyne javanica and races of M. incognita were examined separately in pot experiments to understand their significance in co-existence of the species/races of Meloidogyne in mixed populations in crop fields. The intraspecific interaction in all the nematodes was intense and similar in trend. A step wise increase in the initial population level (P(i)) progressively caused greater suppression of plant growth parameters. Number of females and eggs, and total population (P(f)) of the nematodes increased with an increase in P(i). An increase in reproduction factor (R(f)) also occurred but it declined when P(i) was increased from 1,000 to 10,000 J2. Split inoculation of P(i) 10,000 J2 in two instalments indicated competition between the individuals of the nematodes. Reductions in plant growth, number of females and eggs, P(f) and R(f) were greater in split-inoculations than non-split inoculation of P(i) 10,000 J2. Greater number of mature females and eggs, and higher P(f) and R(f) were obtained with 2,500 + 7,500 J2 than with 5,000 + 5,000 J2 or 7,500 + 2,500 J2. This trend was consistent for all the nematodes. The intense intraspecific interaction of the nematodes may be important in regulating their population growth in addition to their interspecific interactions (competition between the individuals of two different species) to ensure their mixed occurrence in agricultural soils.